Our goal is to understand the molecular mechanisms of solute transport by transmembrane proteins, in particular the sugar uptake in muscle and fat cells which, when impaired, causes type II diabetes. This transport process is mediated by Glut4, a transporter protein that spans the membrane 12 times. Human Glut4 is difficult to study due to its scarcity and heterogeneity. Therefore, we selected a related bacterial protein: the glycerol-3-phosphate (G3P) transporter (GlpT) from E. coli. Mutations in the human G3P transporter are thought to contribute to the susceptibility and severity of diabetes. Knowledge gained on E. coli GlpT will help understand the structure and mechanism of the human Glut4 protein. We will determine the structure of E. coli GlpT, a transmembrane protein, using X-ray crystallography of three-dimensional crystals. The structure will reveal the substrate-binding site and translocation pathway. Knowledge of the structure of GlpT mutants and GlpT in complex with inhibitors/substrates will reveal molecular mechanisms of transport. Mutagenesis and transport assays will provide information on the roles of key residues in substrate selectivity and translocation. The GlpT structure will serve as a paradigm for the mammalian glucose transporters, and other medically relevant proteins such as the dopamine transporter responsible for cocaine addiction. We will build a structural model for the human glucose transporters based on our GlpT structure, combining information from the conserved topology, and biochemical and mutagenesis data on mammalian sugar transporters. This model will be tested by mutagenesis in combination with activity assays on recombinant Glut4, and improved accordingly. Such a model will help us understand the cell's glucose uptake in muscle and fat tissues.
| Karpowich, Nathan K; Song, Jinmei; Wang, Da-Neng (2016) An Aromatic Cap Seals the Substrate Binding Site in an ECF-Type S Subunit for Riboflavin. J Mol Biol 428:3118-30 |
| Sauer, David B; Karpowich, Nathan K; Song, Jin Mei et al. (2015) Rapid Bioinformatic Identification of Thermostabilizing Mutations. Biophys J 109:1420-8 |
| Karpowich, Nathan K; Song, Jin Mei; Cocco, Nicolette et al. (2015) ATP binding drives substrate capture in an ECF transporter by a release-and-catch mechanism. Nat Struct Mol Biol 22:565-71 |
| Mulligan, Christopher; Fitzgerald, Gabriel A; Wang, Da-Neng et al. (2014) Functional characterization of a Na+-dependent dicarboxylate transporter from Vibrio cholerae. J Gen Physiol 143:745-59 |
| Waight, Andrew B; Czyzewski, Bryan K; Wang, Da-Neng (2013) Ion selectivity and gating mechanisms of FNT channels. Curr Opin Struct Biol 23:499-506 |
| Karpowich, Nathan K; Wang, Da-Neng (2013) Assembly and mechanism of a group II ECF transporter. Proc Natl Acad Sci U S A 110:2534-9 |
| Loew, Leslie M; Wang, Da-Neng (2013) Science communication: Quality at stake. Science 342:1169 |
| Wang, Da-Neng; Stieglitz, Heather; Marden, Jennifer et al. (2013) Benjamin Franklin, Philadelphia's favorite son, was a membrane biophysicist. Biophys J 104:287-91 |
| Mancusso, Romina; Gregorio, G Glenn; Liu, Qun et al. (2012) Structure and mechanism of a bacterial sodium-dependent dicarboxylate transporter. Nature 491:622-6 |
| Czyzewski, Bryan K; Wang, Da-Neng (2012) Identification and characterization of a bacterial hydrosulphide ion channel. Nature 483:494-7 |
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